This application requests funds to purchase current-generation instrumentation for the performance of state-of- the-art peptide amide hydrogen-deuterium exchange mass spectrometry (DXMS), to replace the obsolete instrumentation presently used in the UCSD DXMS Resource. Integrated sample preparation, liquid chromatography, and mass spectroscopic instrumentation is requested: 1. A Thermo Fisher LTQ Orbitrap Velos mass spectrometer with electron transfer dissociation (ETD) (ORBXL-0723870) for dedicated DXMS use in the Resource;2. A LEAP Technology H/D-X PAL Hydrogen-Deuterium Exchange sample preparation and injection platform;3. A Waters nanoACQUITY UPLC System for the performance of rapid, high resolution, and high-sensitivity chromatographic separation of proteolytic digests of deuterated protein samples prepared on the LEAP H/D-X PAL. The UCSD DXMS Resource provides facile access to state-of-the-art DXMS technology to NIH-funded investigators. Its twenty-one Major Users have a remarkable record of more than thirty top-tier DXMS-focused publications resulting from work performed in the Resource, and their combined total S10-eligible NIH funding for research that relies on studies performed in the Resource exceeds $9 M in direct costs per year. While the Resource has been highly productive, the sample preparation, chromatographic, and mass spectroscopic instrumentation (a Thermo LCQ Classic and Micromass Q-TOF I), in continuous DXMS use for more than 12 years, are now obsolete, and must be replaced with current generation DXMS-enabling equipment. Because of our capabilities and scientific productivity, requests to the Resource for DXMS study are accelerating. Advances made in the DXMS technology we employ in front of (sample processing chemistries) and after (data processing software), the mass spectrometers have made our old machines the rate-limiting step in both throughput, and quality of DXMS analysis. While any of a number of current-generation mass spectrometers would provide substantial improved throughput and quality of DXMS study, our analysis, and the experience of our consultants indicates that the Thermo LTQ Orbitrap Velos-ETD is a superior and cost-effective instrument for dedicated DXMS use. Together with the requested synergistic sample preparation and LC components, it will allow us to best provide for our current DXMS users, and position us to exploit further advances in DXMS technology, such as ETD-mediated deuteron sublocalization. PUBLIC HEALTH RELEVANCE: At the UCSD DXMS Resource, we provide many protein scientists with the ability to use a technically demanding, but most powerful mass spectrometry-based technology ("DXMS") to study precisely how the proteins they are interested in change shape as they perform their biologic functions. The growing demand for DXMS use requires that the Resource replace the now obsolete equipment that has been used for more than a decade, with the current generation DXMS instrumentation requested in this application.